The present invention relates to the field of well completion assemblies for use in a wellbore. More particularly, the invention provides an improved pressure actuated valve for production zone isolation.
The present invention provides an isolation sleeve assembly which may be installed inside a production screen and thereafter controlled by generating a pressure differential between the valve interior and exterior. In contrast, prior systems required the use of a service string, wire line, coil tubing, or other implement to control the configuration of the isolation valves. Utilization of such systems involves positioning of tools down-hole. Each trip into the wellbore adds additional expense to the well owner and increases the possibility that tools may become lost in the wellbore requiring still further operations for their retrieval.
While pressure actuated valves have been used in certain situations, disadvantages have been identified with such devices. For example, prior pressure actuated valves had only a closed position and an open position. Thus, systems could not reliably use more than one such valve, since the pressure differential utilized to shift the first valve from the closed position to the open would be lost once the first valve was opened. Therefore, there could be no assurance all valves in a system would open.
There has therefore remained a need for an isolation system for well control purposes and for wellbore fluid loss control, which combines simplicity, reliability, safety and economy, while also affording flexibility in use. The present invention satisfies this need, providing an isolation system which does not require tools to shift the valve and allows the use of multiple pressure actuated valves in a production assembly.
Briefly describing one aspect of the present invention, there is provided an isolation assembly which comprises a production string having an interior annulus and an exterior. The production string includes at least one aperture providing fluid communication between the exterior and the interior annulus. Further, a pressure actuated valve is disposed adjacent the aperture. The valve is shiftable by changes in pressure between a locked-closed configuration, an unlocked-closed configuration and an open configuration. In a preferred embodiment, the valve assembly further includes a mechanism for biasing the valve into the open configuration after it has been shifted to the unlocked-closed configuration. In still a further aspect of a preferred embodiment, the valve assembly includes inner and outer sleeves axially displaceable by the generation of a pressure differential between the interior of the production tubing and the exterior. In a preferred embodiment, the inner and outer sleeves define a chamber for transferring a pressure differential into a force acting along the longitudinal axis to urge axial displacement of one sleeve with respect to the other.
The present invention further contemplates the use of a plurality of valves according to the present invention within a single screen assembly and that there may be multiple screen assemblies. Also, if desired to reduce costs of an assembly, a single dump valve having only an open and closed position may be combined with valves of the present design. In such an assembly the pressure differential required to shift the valves from the locked-closed configuration to the unlocked-closed configuration would be less than the pressure required to shift the dump valve to the open position.
Further, valves of the present design may be used in conjunction with known gravel packing and isolation systems. In this manner, gravel packing the formation may be conducted in a standard manner and the formation isolated. Once this is completed, the formation may be brought on-line without running tools back into the wellbore simply by pressuring up the interior of the tubing to open any number of valves according to the present invention.
The present invention further contemplates a method of inserting production tubing, comprising providing a production tubing assembly including a screen, and a pressure actuated isolation valve disposed adjacent the screen. The assembly is inserted into a wellbore until the screen and isolation valve are disposed adjacent a production zone. In a preferred embodiment the isolation valve is initially in a closed configuration, however, it is contemplated that the valve may be manipulated into such a configuration after placement. When desired, a pressure differential is created between the exterior of the production tubing and the interior, the pressure differential tends to shift the pressure actuated valve from a locked-closed configuration to an unlocked-closed configuration. Thus, in the first valve shifting operation the valve stays in a continuously closed state. In a preferred embodiment, the pressure in the tubing is initially increased with respect to the pressure surrounding the production assembly to move the valve to an unlocked, yet closed configuration. Once unlocked, the pressure differential is decreased to allow the valve to move to an open configuration to permit fluid flow through the production screen. In multiple zone completions, the method may preferably include passing a further production tubing string through the isolation valve to reach a lower production zone. It will be understood that the pressure actuated valve of the present invention may be actuated with such a second production tubing in place in the wellbore.
It is an object of the present invention to provide a versatile isolation system that combines simplicity, reliability, safety, and economy with optional methods of operation.
Another object of the present invention is to provide an isolation valve that may be shifted without the use of tools inserted into the wellbore.
Still another object of the present invention is to provide an isolation system that may be permanently installed inside the production screen at the surface prior to running into the well.
Yet a further object of the present invention is to provide a pressure actuated valve that may be used in conjunction with a plurality of similar valves to provide reliable shifting of all valves simultaneously.
It is a further object to provide an isolation system which is simpler to install and operate, and which provides immediate access to a zone of interest.
According to one aspect of the invention, there is provided a valve for a production assembly for the production of minerals from a well, the valve having a tube having at least one opening; a sleeve having at least one other opening and being movably connected to the tube, wherein the tube and sleeve are configurable in at least locked-closed, unlocked-closed and open configurations, wherein the at least one opening and the at least one other opening are adjacent in the open configuration and nonadjacent in the locked-closed and unlocked-closed configurations; and a chamber between the tube and the sleeve, wherein a pressure within the chamber unlocks the lock and configures the tube and sleeve between the locked-closed and unlocked-closed configurations.
According to a further aspect of the invention, there is provided a valve for a production assembly for the production of minerals from a well, the valve having: a tube having at least one hole; a sleeve, wherein the sleeve and tube are configurable between at least locked-closed, unlocked-closed and open configurations, wherein the sleeve shuts the at least one hole in the locked-closed and unlocked-closed configurations and the sleeve opens the at least one hole in the open configuration; and a pressure activated control mechanism.
According to still another aspect of the invention, there is provided a production assembly for producing mineral from a production zone, the assembly having: a production string; a production screen; a valve having: a tube having at least one hole; a sleeve, wherein the tube and sleeve are configurable between at least locked-closed, unlocked-closed and open configurations, wherein the sleeve shuts the at least one hole in the locked-closed and unlocked-closed configurations and the sleeve opens the at least one hole in the open configuration; and a pressure activated control mechanism.
According to another aspect of the invention, there is provided a method for producing mineral from a production zone, the method having the steps of: placing a production assembly adjacent the production zone, wherein the production assembly having: a production pipe; a production valve comprising: a tube having at least one hole; a sleeve, wherein the tube and sleeve are configurable between at least locked-closed, unlocked-closed and open configurations, wherein the sleeve shuts the at least one hole in the locked-closed and unlocked-closed configurations and the sleeve opens the at least one hole in the open configuration; and a pressure activated control mechanism which reconfigures the sleeve and tube between the locked-closed configuration and the unlocked-closed configuration; inducing a pressure differential between an interior of the production assembly and an exterior of the production assembly, wherein the pressure differential is sufficient to activate the pressure activated control mechanism.
Further objects and advantages of the present invention will be apparent from the description of the preferred embodiment which follows.